Fish tank



FIG. 1 is a perspective view of the fish tank showing my new design;

FIG. 2 is a perspective view thereof;

FIG. 3 is a front plan view thereof;

FIG. 4 is a back plan view thereof;

FIG. 5 is a left plan view thereof;

FIG. 6 is a right plan view thereof; and,

FIG. 7 is a downward plan view thereof.

Portions of the fish tank shown in broken lines in aforementioned FIGS. 3 and 4 form no part of the claimed design. 

CLAIM The ornamental design for a fish tank, as shown and described. 